{{#xlsxAdd "xl/worksheets/sheet1.xml" "worksheet.sheetData[0].row"}}
<row r="1">
    <c r="A1" t="inlineStr">
        <is>
            <t>I want to be a merged cell</t>
        </is>
    </c>
</row>
{{/xlsxAdd}}

{{#xlsxReplace "xl/worksheets/sheet1.xml" "worksheet.mergeCells"}}
    <mergeCells>
        <mergeCell ref="A1:C2"/>
    </mergeCells>
{{/xlsxReplace}}


{{{xlsxPrint}}}